Single use disposable syringe

ABSTRACT

A single use disposable syringe having a piston axially slidable in a barrel for undergoing a retraction movement to fill the barrel with fluid and a forward movement to discharge the fluid from the barrel. An operating rod projects from the barrel for operating the piston and the rod is operatively connected to the piston with capability of relative axial movement therebetween to approach the piston during its forward movement. A flexible finger has one end connected to the piston or rod and a cutting element is provided on the flexible finger in spaced relation from the connected end thereof and facing the barrel. During retraction movement of the piston, the cutting element is retracted from the barrel whereas during forward travel of the piston and approach of the operating rod towards the piston, a deviation member displaces the flexible finger outwardly to produce cutting of the barrel by the cutting element to render the barrel subsequently unusable.

DESCRIPTION

1. Field of the Invention

The present invention relates to disposable syringes which are renderednon-reusable after a first injection therewith.

2. Background and Prior Art

Syringes disposable after a single use are being used more and more toavoid the risks of contamination from using a syringe poorly sterilizedafter a first use.

However, contaminations are due to the use by drug-addicts of previouslyused syringes which are not sterilized or poorly sterilized.

In order to avoid such accidents, syringes have been proposed which arerendered automatically non-usable after a first injection.

U.S. Pat. No. 3 934 586 (Easton et al) describes pre-filled syringeswhich make it possible to inject several successive doses.

The operating rod of these syringes bears stops which abut one anotheron the end of the barrel and which are broken along an oblique line ofmaximum weakness which leaves a sharp edge which scores the wall of thebarrel. Such syringes cannot be re-used.

Patent De-A-1 965 761, FR-A-2 027 681, U.S. Pat. No. 3 667 657(Chiquiar-Arias) describe pre-filled syringes which comprise a smallknife which is fixed laterally on the operating rod and which is engagedin an opening in the cylindrical barrel. These syringes cannot be soldempty to be filled by the user as, as soon as the piston is driven intothe barrel, the knife cuts the latter.

U.S. Pat. No. 3 951 146, DE-A-2 354 628, FR-A-2 204 429 (Chiquiar-Arias)describes syringes in which the operating rod bears a casing or a notchin which is housed a small knife which is pushed radially by a springand which presents a rounded rear edge and a cutting front edge. It ispossible to withdraw the piston rearwardly in order to suck liquid intothe barrel without scratching the wall of the barrel. In order to drivethe piston to the bottom of the barrel, a protection sheet is engagedbetween the wall of the cylindrical barrel and the cutting blade whichis removed thereafter.

The problem to be solved is to provide self-destroying syringes whichmay be sold empty and which make it possible firstly to drive the pistonin the barrel in order to drive out the air without scratching thebarrel, then to withdraw the piston rearwardly in order to suck in aliquid without scratching or cutting the wall of the barrel, then todrive the piston again into the barrel in order to inject the dose ofliquid contained therein, while cutting or scratching or breaking thewall of the barrel in order to render the syringe unusable a secondtime.

SUMMARY OF THE INVENTION

A syringe according to the invention comprises a cylindrical barrel, apiston displaceable inside said barrel, a rod for moving said piston anda cutting member which scratches or cuts or breaks the wall of saidbarrel during the injection of the liquid contained in said barrel.

The solution of the aforesaid problem consists in a syringe in which oneend of the rod and said piston are connected by means which allow arelative axial displacement and either the rod or piston bears at leastone flexible finger, which bears at its free end a cutting member,whilst the other bears a deviation means which cooperates with saidflexible finger to deform the latter by pushing said cutting memberoutwardly when said end of the rod and said piston approach one another,with the result that, when the rod is withdrawn rearwardly in order tofill the syringe with the liquid to be injected, said flexible fingersoccupy a position in which said cutting members are retracted insidesaid barrel and do not touch the wall thereof and when said piston isdriven into said barrel, pushing on the rod to inject the liquid, saidflexible fingers move apart and said cutting members are pushedoutwardly and cut or scratch the wall of the barrel, which renders thesyringe unusable a second time.

According to a first embodiment, said piston or one end of the rod bearsone or more ramps inclined with respect to the axis of the syringeagainst which said flexible fingers slide, moving apart towards theoutside when the rod and said piston approach each other axially andretracting towards the inside when the rod and said piston approach eachother axially and retracting towards the inside when the rod and saidpiston move apart axially from each other.

According to another embodiment, each of the flexible fingers isconnected to the piston or to one end of said rod by an articulatedconnected rod which pushes said flexible finger outwardly when saidpiston and said rod approach each other axially and which returns saidflexible finger inwardly when said piston and said rod move apartaxially from each other.

A process for manufacturing a non-reusable syringe according to theinvention comprises the following operations:

connecting one end of the rod to said piston by connected means whichallows a relative axial displacement of small amplitude and providingthe rod or piston with at least one flexible finger which bears acutting member while the other is provided with a deviation means whichcooperates with said flexible finger in order to move the fingeroutwardly when said rod and said piston axially approach each other andto allow the finger to retract inwardly when said piston and said rodmove axially away from each other;

placing between a flange of the barrel and a disc on the end of the roda safety distance piece in order to avoid, in the event of accidentalabutment on the rod during handling, packing or unpacking of thesyringe, piercing of the wall of the barrel, which would prematurelyrender the syringe unusable;

connecting the end of said provided with the needle support or anincorporated needle to a suction means to drive said piston in saidbarrel without said cutting members cutting or scratching said barrel.

The invention results in novel disposable syringes which cannot bereused after a first injection.

The syringes according to the invention have the advantage of being ableto be delivered, unfilled, with the piston driven in the barrel of thesyringe, this operation being effected in the factory by connecting thesyringes to a suction means which sucks the piston towards the bottom ofthe syringe so that the cutting members are retracted during thisoperation and do not risk scratching or cutting the wall of the barrel.

The syringes according to the invention also have the advantage that thecutting members are pushed radially by a force which is proportional tothe axial thrust exerted on the rod during injection, so that thepenetration of the cutting members in the wall of the barrel is betterensured than in the known syringes where the knife is pushed radially bya spring exerting a constant thrust.

The freedom of relative axial displacement of the rod with respect tothe piston of the syringe makes it possible to obtain a spacing of theknives towards the outside when one presses on the rod but also aretraction of the knives towards the inside when the rod moves axiallyaway from the piston, i.e. when one pulls on the rod to suck liquid orwhen the piston is sucked to drive it in the syringe, with the resultthat, during these two operations, the cutting members do not riskcutting or scratching the wall of the barrel.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description refers to the accompanying drawings whichshow, without any limiting character, embodiments of syringes accordingto the invention.

FIG. 1 shows in axial section a disposable syringe according to a firstembodiment.

FIG. 2 shows in partial axial section the same disposable syringeaccording to the invention during use.

FIG. 3 is a transverse section along line III--III of FIG. 2.

FIG. 4 shows in axial section a second embodiment of disposable syringesaccording to the invention.

FIG. 5 shows, in partial axial section, the same embodiment as in FIG.4, under conditions of use identical to those of FIG. 2.

FIG. 6 shows in axial section a third embodiment of disposable syringesaccording to the invention.

FIG. 7 shows in partial axial section the same disposable syringe inuse.

FIG. 8 shows in partial axial section a fourth embodiment of disposablesyringes according to the invention.

FIGS. 9 and 10 show steps for carrying out the process of manufactureaccording to the invention.

FIGS. 11, 12 and 13 show three particular embodiments of the cylindricalbarrel of disposable syringes according to the invention.

FIG. 14 is a section along XIV--XIV of FIG. 11.

FIG. 15 is a section along XV--XV of FIG. 12.

FIG. 16 is a section along XVI--XVI of FIG. 13.

DETAILED DESCRIPTION

As indicated in FIGS. 1 to 3, a disposable syringe comprises acylindrical barrel 1 with axis XXI which is provided at one end with aneedle 2. An operating rod 8 and a piston 6 which slide in said barrel.

The rod 8 has a groove 11, extending longitudinally and parallel to theaxis, XXI said groove being bounded at one end by a disc 15 and at theother end by a stop 12 connected to rod 8.

The barrel 1 advantageously comprises at one end a flange 5 on which isadded, after positioning the rod 8 in said barrel, a guide bead 4 whichpenetrates in said groove.

The bead 4 extends into 11 and groove allows the rod 8 to slide withrespect to said barrel but prevents rotation of said rod with respect tosaid barrel.

Said bead 4 has a face 13 which forms a stop, with the stop 12 connectedto the rod, 8 with the result that, when an attempt is made to extractsaid rod from said barrel, the face 12 comes into contact with the stop13 and therefore prevents the extraction.

This prevents the user from removing the cutting members to be describedhereafter.

In a preferred embodiment, the wall of said barrel comprises at minimumone zone 3 of least resistance, for example a groove which extends alonga generatrix of said cylindrical barrel substantially over the entirelength of said barrel.

Said piston advantageously comprises sealing means 7.

The syringe according to the invention comprises at least one pointedand cutting projection of any other cutting or breaking means 9 such asa blade, sharp edge or knurl 30 adapted to produce grooving, permanentdeformation, cutting perforation or breaking into fragments of saidbarrel, with the result that the latter can no longer cooperate withsaid piston so as to permit pumping of the fluid, and therefore itprevents subsequent use of the syringe for the purpose of injecting saidfluid.

In the following specification, in order to facilitate reading thereof,said means will be designated by the generic term cutting member 9.

In the embodiments according to the invention, said cutting members aremounted at the free end of flexible fingers 10 which are themselvesconnected to an end of said rod 8 or said piston 6.

In the embodiment shown in FIG. 3, the syringe comprises two flexiblefingers.

In the embodiments according to the invention shown in FIGS. 1, 2, 4, 5,6, 7, 8, 9, said flexible fingers are connected to an end of rod.

In a first embodiment according to the invention, said piston comprisesat least one deviation surface 16 which is constituted for example by atruncated surface as shown in FIGS. 1 and 2, or by an oblique ramp withrespect to axis XX₁, against which the fingers come into contact.

In FIG. 1, said deviation surface cooperates with said flexible fingerswhich occupy a position in which the latter are retracted inside saidbarrel and do not touch the wall thereof.

In FIG. 2, said deviation surface cooperates with said flexible fingersin order to deform them by pushing said cutting members outwardly whensaid end of the rod and said piston approach each other, subsequent tothe application of a thrust represented by arrow P on rod so that saidcutting members cut or scratch the wall of said barrel, which rendersthe syringe unusable a second time.

Such changes in position of said flexible fingers are due on the onehand to the flexibility of the fingers and on the other hand to therelative approach or moving apart of said piston and said manoeuvringrod, these movement being said possible by the particular structure ofthe connecting means between and said piston.

In fact, in this embodiment, FIGS. 1 and 2 show that said pistoncomprises a rod 17 and a head 18 which terminates in a face 21, whilethe opposed end of rod 8 comprises a housing 31 limited by a bottom face20, said flexible fingers comprising catches 19.

The flexibility of the fingers makes it possible, when assembling thesyringe, for said head 18 on the piston to penetrate in housing 31 inthe rod so that catches 19 engage behind head 18 whereby the rod andpiston are connected with freedom of relative axial displacement.

FIG. 2 shows that such relative axial displacement is limited in thedirection of approach between said rod and said piston, by the contactof said surface 21 and of said bottom face 20, with the result that thespacing apart of the flexible finger subsequent to such approach is thuslimited.

Moreover, FIG. 3 shows that said flexible fingers comprise bearing faces22 and 23 located in the immediate vicinity of the cutting members 9,said bearing faces cooperating with the inner wall of said barrel, thuslimiting the spaced apart relationship of said cutting members, with theresult that, during cutting, the cutting members do not project outsidesaid barrel and cannot injure the user.

In FIGS. 4 and 5, analogous parts of FIGS. 1 and 2 are shown with thesame references.

FIGS. 4 and 5 show another embodiment according to the invention inwhich said flexible fingers 10 are connected at one end to rod 8 and atthe other end to said piston 6 via connecting rods 24 articulated attheir two ends, the connecting means between rod 8 and piston 6 thusdefined allowing the spacing apart and retraction of said cuttingmembers corresponding respectively to the relative approach and spacingapart of said rod and said piston.

In fact, FIGS. 4 and 5 show that said connecting rods 24 comprise asubstantially rigid central part which itself comprises a surface 25which forms a stop, and two end of a section and rigidity substantiallyless than the central part with the result that said ends of theconnected rod which are connected, one to said piston, the other to saidflexible finger, may be deformed and thus constitute an articulationjoint.

FIG. 4 shows that, after application of a traction force to rodrepresented by arrow F, the forces of traction are transmitted by saidflexible fingers to said connecting rods and by said connecting rods tosaid piston.

Taking into account the resistance to sliding of said piston in saidbarrel due to the friction of the latter and said sealing means, theends of said connecting rods performing the role of articulation jointson being deformed, said connecting rods move, provoking retractioninside the barrel of the cutting members simultaneously with therelative moving apart of said rod and of said piston.

FIG. 5 shows that after the application of a thrust on the rod,represented by arrow F, the force transmitted by said flexible fingerslead to a deformation of the ends of the connecting rods 24 to causedisplacement of the cutting members 9 towards the wall of said barrel,with the result that, when the piston is driven into said barrel, saidcutting members cut or scratch said inner wall of said barrel.

FIGS. 6 and 7 show a third embodiment according to the invention. Theanalogous parts of FIGS. 1 and 2 are represented by the same references.

Piston 6 comprises a rod 17 and a head 18 slidable in a housing 31arranged at the end of rod 8 which itself comprises catches 27 and abearing face 28, which allows a relative axial displacement between therod 8 and the piston 6.

Inside said piston rod 17 are two inclined surfaces 16 which form twooblique ramps which converge in the direction of the rod 8.

An elastic pin 38 in the form of a U constitutes a pair of flexiblefingers whose ends are bent and bear cutting members 9.

Said pin is seemed to rod 8 by a connecting means 29 such as a clamp,ring or any other equivalent fixing means.

In FIG. 6, the surfaces 16 cooperate with said flexible fingers so thatthe latter retract inside said cylindrical barrel without touching thewall thereof, when said piston moves away from said rod.

FIG. 7 shows that, during injection of the liquid under the action of athrust by the user on rod 8, represented by arrow P, said deviationsurfaces excert forces outwardly, due to the approach of said piston andsaid rod, to cause said cutting members to cut said wall.

In the embodiment shown in FIGS. 6 and 7, the deviation surfaces, in theform of inclined ramps, may advantageously be constituted by the bottomof a groove made in said rod 17, the sides of said groove serving toguide the flexible fingers during the relative movements between saidpiston and said rod 8.

FIG. 8 shows a variant according to the invention, in which the cuttingmembers are constituted by knurls 30, particularly for when said barrelis made of a breakable material such as glass, plastics materials ofpolycarbonate type, which, under the pressure exerted by said knurlsaccording to the same principles as developed for the other embodiments,will break into fragments or burst.

In this embodiment, the cylindrical barrel may be covered on the outsidewith a supple film which forms a jacket avoiding dispersion of thefragments resulting from the breakage. The breakage advantageouslyoccurs in the zone of least resistance 3 constituted by a groove made inthe barrel, said groove being filled with a supple resin which avoidsthe dispersion of the fragments resulting from the breakage.

FIG. 9 shows the process of manufacturing the disposable syringesaccording to the invention and more particularly the process whichconsists in guiding said piston in the bottom of said barrel withoutdamaging the latter and enabling empty syringes ready to be filled bysuction to be delivered.

At least one tube 32, is equipped with a connecting device 33 fixed onthe end of the needle 2 of the syringe.

Tube 32 is connected at its other end to suction means 34 such as apump, for example.

The four principal pieces of the syringe, viz. said barrel, said piston,said rod, said bead, may be manufactured separately.

In that case, said need an said piston is engaged in said housingprovided in said rod.

In a variant, the rod and the piston are assembled together.

Said piston is then presented in said barrel so that the sealing means 7are introduced as shown in FIG. 9, taking care to maintain said rodremote from said piston thanks to the structure of the connecting meansdescribed in the above paragraphs, with the result that said flexiblefingers are in a retracted position and do not damage said barrel whenthey are made to penetrate therein.

When said suction means is actuated, said piston is subjected to a forcedue to the difference in pressure existing between its faces, whichforce produces its displacement towards the bottom of said barrel: theflexible fingers remain in their retracted position during thismovement. The piston drives the rod in its movement. Finally, said bead4 is mounted on said flange and there is placed between the flange 5 ofthe barrel and the disc 15 of the end of the rod 8 as shown in FIG. 10,a safety spacer device 39 in order to avoid, in the event of accidentalpressure on the rod, 8 during handling, packing or unpacking of thesyringe, cutting of the wall of the barrel before use, which wouldprematurely render the syringe unusable.

FIGS. 11 to 16 show three other embodiments of a syringe according tothe invention in which said barrel comprises said zone of leastresistance 3 which extends along a generatrix of said cylindricalbarrel.

In an embodiment shown in FIGS. 11 and 14, said wall of said barrelcomprises two projecting zones 35 which extend along two generatrices ofsaid barrel, on either side of said zone of least resistance 3, and formtwo beads so that, when said barrel is cut by said cutting members, saidprojecting zones prevent any accidental contact between said cuttingmembers and the user.

FIGS. 12 and 13 show another variant in which said wall comprises onesingle projecting zone, in the form of a tongue 36, which partiallycovers said zone of least resistance 3.

FIGS. 13 and 16 show a variant according to the invention in which saidprojecting zones 35 located on either side of zone 3, join to form atongue 37 which completely covers said zone 3.

The embodiments of a syringe according to the invention shown in FIGS.11 to 16 make it possible to avoid andy risk of said cutting membersinjuring the user.

The relative arrangements of the fingers and the deviation surfaces withrespect to the piston and to the rod may, of course, be reversed withoutthe operation being modified.

I claim:
 1. A singe use disposable syringe comprising:a barrel having anaxis, a piston member axially slidable in said barrel in a retractionmovement to fill the barrel with fluid and a forward movement todischarge fluid from the barrel, an operating rod member projecting fromsaid barrel for operating said piston member and being operativelyconnected to said piston member with capability of relative axialmovement therebetween to approach said piston member during forwardmovement of said piston member, a flexible finger having an endconnected to one of said members, cutting means on said flexible fingerspaced from said one end thereof and facing said barrel, and deviationmeans for displacing said flexible finger outwardly during approach ofsaid operating rod member towards said piston member upon forwardmovement of said piston member to produce cutting of said barrel by saidcutting means to render said barrel subsequently unusable, said flexiblefinger having a normal position, when not displaced by said deviationmeans, in which said cutting means is retracted from said barrel duringretraction movement of said piston member.
 2. A syringe as claimed inclaim 1, wherein said deviation means comprises an oblique ramp havingan inclined surface contacting said flexible finger to move said fingertowards said barrel when said operating rod member and said pistonmember approach one another.
 3. A syringe as claimed in claim 1, whereinsaid deviation means comprises a body have a conical surface contactingsaid flexible finger.
 4. A syringe as claimed in claim 1, comprising asecond flexible finger and corresponding cutting means on said onemember in diametric opposition to the first said flexible finger.
 5. Asyringe as claimed in claim 1, wherein said deviation means comprises aconical surface slidably emerging said finger member.
 6. A syringe asclaimed in claim 1, comprising means coupling the rod member and thepiston member for relative axial movement, comprising a piston rod onsaid piston member and a head on said piston rod, said rod member have ahousing in which said head is slidable and catch means retaining saidhead in said housing.
 7. A syringe as claimed in claim 1, wherein saiddeviation means comprises an articulated connecting rod joining saidpiston and rod members to permit limited relative axial movementthereof, said articulated connecting rod being connected to saidflexible finger to produce outward displacement thereof when the pistonand rod members approach one another.
 8. A syringe as claimed in claim1, wherein said barrel is constituted of a breakable material, saidcutting means comprising a barrel member which breaks said barrel whendisplaced thereagainst.
 9. A syringe as claimed in claim 1, comprisingan elastic pin with flexible arms each constituting one said flexiblefinger.
 10. A syringe as claimed in claim 1, wherein said barrel has azone of minimum resistance facing said cutting means.
 11. A syringe asclaimed in claim 1, wherein said barrel is cylindrical and has a zone ofminimum resistance facing said cutting means extending along ageneratrix of said barrel.
 12. A syringe as claimed in claim 11,comprising a tongue on said barrel covering at least a portion of saidzone of minimum resistance.
 13. A syringe as claimed in claim 1,comprising a bead on said barrel engaging said rod member to permitsliding movement of said rod member in said barrel while preventingrelative rotation between said rod member and said barrel.
 14. A syringeas claimed in claim 13, comprising flange means on said operating rodmember cooperating with said bead for limiting the movement of said rodmember in said barrel.
 15. A syringe as claimed in claim 14, comprisingremovable stop means interposed between said operating rod means andsaid barrel to temporarily block relative movement therebetween.
 16. Asyringe as claimed in claim 1, comprising means for limiting outwardmovement of said flexible finger to prevent said cutting means fromextending outwardly of said barrel.